A large fraction of yield losses in wafer fabrication or processing of semiconductor devices is attributed to contamination. Contaminants can be organic or inorganic particles, films or molecular compounds, ionic materials, or atomic species. Particularly problematic, however, is contamination from abrasive particles used during processing, such as, for example, planarization. For example, during chemical mechanical planarization or polishing (CMP), a rotating substrate of semiconductor material is held against a wetted planarization or polishing surface under controlled chemical liquid (i.e., slurry), pressure, and temperature conditions. The liquid typically consists of an abrasive component, such as alumina, silica, or similar particulates, although, alternatively, a pad could include the abrasive component. Once the planarization or polishing is complete, abrasive particles typically remain on the surface of the substrate.
Thus, the primary contaminants that need to be removed from the substrate surface during/after processing, such as planarization or polishing, and prior to subsequent processing steps are alumina, silica, and oxides. Other contaminants that can also be problematic include ionic, atomic, or molecular species containing sodium, potassium, lithium, calcium, boron, manganese, sodium, titanium, zirconium, magnesium, iron, copper, nickel, gold, silicon, and aluminum. Such contiminants may diffuse into the surface of the substrate and down fracture paths.
Also, the presence of contaminants during substrate processing has become particularly problematic in high density, large scale integration (LSI) technology. For example, contaminants can cause a device to fail by improperly defining patterns, creating unpredictable surface topography, inducing leakage currents through insulating layers, or accelerating device wearout.
It has been reported that phosphonic acid chelating agents added to a SC-1 wet cleaning solution (a mixture of NH.sub.4 OH, H.sub.2 O.sub.2, and H.sub.2 O) of an RCA clean commonly used to remove particles and organic contaminants on silicon surfaces subsequent to planarization processing, reduces certain metallic contamination deposition on a silicon substrate. This conclusion was reached in the article entitled "Thin-Oxide Dielectric Strength Improvement by Adding a Phosphonic Acid Chelating Agent into NH.sub.4 OH--H.sub.2 O.sub.2 Solution" by Akiya et al., J.Electrochem. Soc., Vol.141, No. 10, October 1994. Also, it has been demonstrated that water soluble multidentate chelating agents, particularly water soluble bidentate ionic chelating agents, such as 1,2-ethylenediphosphonic acid (EDP), can be used during planarization processing to remove metal ion contaminants, as disclosed in U.S. patent application Ser. No. 08/682,308, filed on Jul. 17, 1996, entitled "A Planarization Fluid Composition Including Chelating Agents and Planarization Method Using Same."
Another problem that has not been adequately addressed is the cleaning of the planarization or polishing surface both during and after processing. When planarization or polishing surfaces are used with abrasive slurries, it is important to prevent the buildup of abrasive particulates and other contaminants on such polishing surfaces. When abrasive pads are used, it is important to prevent the buildup of metal and metalloid ions and oxides, for example, on such abrasive pads. Such contaminants shorten the effective lifetime of processing equipment and should be removed to ensure precise processing of substrates during planarization or polishing without excessive contamination of the substrates.
Thus, compositions and methods are still needed to reduce, for example, the amount of metal and metalloid ion and abrasive particulate contamination of, for example, the substrate being processed and the processing equipment used. The present invention as described below provides such compositions and methods.